Modelling a Aircraft - F9F-5

 From:  Michael Gibson
2036.63 In reply to 2036.59 
Hi Kevin, I thought a few details on how I arrived at that model and a few other tips and background might be useful.

If you want to end up with a shape that has a kind of long and evenly smooth type form it is really hard to get that by building things only in small individual panels that touch edge to edge. Even when you have continuity control for matching the edges it is still not a good way to do it, because the continuity control will tend to bend around the area just near the ends of your patch, which produces kind of lumps which are technically smooth where they touch edge to edge but does not have the kind of totally even distribution that you want in a case like this. For it to work your initial curve network has to have a very even curvature distribution in it and it is hard to create that.

There are several industries that do construct their smooth things in a panel by panel basis, however it is a very time consuming way to do it. They have some fancy software to help a bit, but really the role of the fancy software tends to be fairly exaggerated for this particular stuff, the results are more about a lot of expertise in setting up the framework and also in nudging surface control points around, and probably the biggest ingredient is a lot of time and effort spent on the problem. It is just not a very practical method for your kind of situation.

So for a project like this I would really avoid that kind of a strategy.

Instead to get smooth pieces it works a lot easier to build surfaces that are larger and also try to be more sparing in the number and complexity of curves used.


So I started by drawing a profile following the edge of the fuselage in the top view.

Then I took a look at the front view, and I noticed that this cross-section pointing to in red here:



seemed to be an exact circle.

So exact circle made me think of revolve, one of the nice things about revolve is that it will always make a very predictable and evenly shaped smooth form. So it is nice to use it when possible.

So the revolve builds a large smooth section of the fuselage all at once:




That's a good example of the kind of componentization that I was referring to earlier.

Forget about some of the other pieces like the canopy for a minute, just focus on getting a particular element of the model right. Later on the canopy will get built separately and then blended in to the main shape.

It probably would have been a good idea to rotate the profile 90 degrees down so that the seam was on the bottom, that would just make a more symmetric topology for later on when putting in wings.

Then looking from the side, it seemed like the front part was good, but along the back part there is kind of a rising section. So I turned on surface control points and pulled some of the up to stretch out that part a bit, and to start some of the transition into the tail:






Then I traced a profile of the canopy from the front and side:



Note how the side profile is extended beyond where the line ends stop on the blueprint, this kind of extension is a big ingredient for building components so that they punch through each other and can be intersected:




First I tried doing a sweep, using side profile as the rail:




But that kind of gave a sort of flat-sided shape (may be just I did not pick a good profile to do...), I noticed in the photos that the canopy has a lot more rounded bubble type shape to the sides:




Instead of messing with the profile much, I decided to try a rail revolve, which is a variant of revolve that can also take a shaping curve. So in this case the revolve profile is the long side view piece, the front profile is the rail, and the axis is snapped to the endpoints of the long side view piece, that generates this individual piece:



And together with the main body:



Then to fuse them together, select both of them, run Edit/Trim, at the "Push cutting objects or Done for mutual trim" prompt, press done or right click to say that you want one to cut the other, switch to Mode: Keep and pick on the 2 pieces you want to keep and then Right-click and the inside pieces will removed. Then join them together, and I used Fillet to round off the edge, but switching the Shape: option from the standard Shape: Circular to Shape: G2 Blend - that will put in a more organic connecting piece that is not an exact circular shape, it tends to make for a more seamless and less distinct boundary to the blend.

I hope this may be useful to you or others, I mean you can see the results give you smooth surfaces without the kind of warping or bunching that you were seeing with the other kind of strategy.

Unfortunately I probably won't be able to do any more extensive posts on this, got to get some work done on the software too! :)

- Michael